The Burden of Obesity Among Young Urban People

Among U.S. children aged 6 to 11, the prevalence of being overweight has nearly quadrupled. There is also a disproportionately high rate of obesity in minority children and those who live in low-income urban neighborhoods. For example, almost half of the children in New York City public schools are overweight, and about 25 percent of them are obese. Thirty-one percent of the city's Hispanic children are obese.

While genetic factors can create a predisposition, it is a combination of environment and heredity that accounts for most cases of obesity. Especially to blame are high-calorie fast foods, "junk" foods full of refined carbohydrates and sugars and sugar-rich sodas in combination with decreased physical activity. The current decline in exercise in American children is linked to increased television viewing, lack of access to playgrounds or organized sports activities and concerns for physical safety that lead parents to keep their children indoors. All of these factors, along with the educational and economic level of parents and cultural perceptions of obesity, increase the risk of childhood obesity in the urban built environment.

The Mount Sinai Children's Environmental Health Center (MSCEHC) is planning to pursue a Community-Based Participatory Research (CBPR) project on obesity in East Harlem, a predominantly low-income and minority community that has the highest prevalence of adult obesity of any neighborhood in New York City. Working with community leaders and health advocates, MSCEHC will study structural features of the urban built environment that may lead to obesity with particular attention to: 1) accessibility of parks and recreational areas, 2) opportunities and spaces for physical activity, 3) safety, 4) neighborhood aesthetics and 5) accessibility of healthy foods.

In addition, MSCEHC plans to assess neighborhood children's biological levels and environmental sources of exposure to endocrine disruptors (EDs), chemicals that may alter endocrine function. Synthetic EDs, like phthalates and bisphenol A, are found in plastics and personal-care products, and some natural plant phytoestrogens may also have ED effects.

An interesting and unanswered question is whether in-utero or early childhood exposures to EDs may influence normal body growth and risk of obesity, perhaps in a complex interplay with diet, physical-activity level and individual susceptibility factors. Organochlorine EDs (in industrial PCBs and the pesticide DDT) have, for example, been shown capable of profoundly influencing growth by lowering birth weights and decreasing body size. Exposures to DDE (the metabolized form of DDT in the body) have been associated with higher height and weight in boys, and PCBs have been associated with higher weight in girls.

Recent national surveys conducted by the CDC found that residues of EDs are present almost universally in Americans, but that the highest levels are found in children and in minorities. The children of East Harlem face increased body burden of EDs along with high rates of obesity and scarce space in which to actively play. It is imperative that the health threats faced by these vulnerable populations continue to be identified and treated. n